Method for the pyrolysis of petroleum oils and apparatus therefor



HUU J- A ril 16, 1935. N. E. LOOMIS 1,998,248

METHOD FOR THE PYROLYSIS OF PETROLEUM OILS AND APPARATUS THEREFOR Filed Jan. 27, 1928 Acc' UMULA TOR ,SEPARA 7-012 SOAKl/VZ? 22 UN awvwwbom Jaffianze Z (5. Loomzs Patented Apr. 16, 1935 UNITED STATES LAUI I I H11 PATENT OFFICE METHOD LEUM OILS AND FOR THE PYROLYSIS OF PETRO- APPARATUS THEREFOR ration of Delaware Application January 27, 1928, Serial No. 249,782

2 Claims.

This invention relates to a method and apparatus for the pyrolysis of petroleum oils and production of gasoline from the products of pyrolysis. The invention will be understood from the following description read in conjunction with the drawing which is a vertical plan with parts in section of a preferred embodiment of an apparatus in which my method may be carried into effect. The drawing and method of operation will be conjointly described.

Oil is forced under pressure by means of the pump I into the pipe 2 discharging into the cracking coil 3. The coil 3 may be of any suitable type and is surrounded by a suitable refractory setting 4 heated by means of the burner 5. The oil passing through the coil is heated to a cracking temperature and discharged without isubstantial loss of heat through the pipe 6 into ;'the soaking drum 1. The drum 1 is surrounded .by suitable insulating material 8 whereby radiation from the drum is inhibited and the contents are held at a cracking temperature for a substantial period. The drum may be operated at any cracking temperature and the contents of the drum may be principally in liquid or gas phase or in any proportion of liquid and gas phases. Cracked material is continuously withdrawn through the pipe 8'.

The herein-above described parts of the system ordinarily operate at relatively high pressures ranging from to several hundred lbs. gauge per square inch. This pressure is substantially reduced at the reduction valve 9 and cracked material, at reduced pressure principally in the vapor phase, passes through the pipe I0 into the separator H in which tarry material separates out while substantially tar-free material is conducted away through pipe I2. The tar which separates in II is continuously or periodically withdrawn through pipe l3 by means of pump l4 and after passing through any suitable cooler which has been diagrammatically indicated by I5, is passed through pipe 16 to any suitable accumulator. The cracked material passing off through pipe i2 enters the rectifying column I! either near the base or at an intermediate point. The column I! may be of any suitable type adapted for rectification but consists preferably of a columnar chamber spanned by the transverse partitions l8 which in turn carry overflow pipes l9 and vapor distributors (bell caps) 20. Vapors passing up through the column I! are partially condensed at or near the top of the said column by means of cooling coils such as 2| and 22. The function of the cooling coils is to produce a condensate which passes in a general downward direction from plate to plate in contact with ascending vapors and thereby operates to control the composition of the vapor phase withdrawn through the pipe 23. Condensate collecting in the base of the column l1 may be heated by means of the coil 24 supplied with any suitable heating medium such as steam through the pipes 25 and 26 and a part of this condensate is continuously withdrawn through pipe 21 to accumulator 28.

A part of the feed stock for the cracking coil is forced under pressure by means of the pump 29 through pipe 30, coil 2| and pipe 3 I, which in turn discharges into the accumulator 28. This is a preferred method of providing condensate for the column I! while simultaneously preheating the feed stock, although, of course, any alternative cooling means may be employed in the column. The combined feed stock and condensate from accumulator 28 passes through pipe 32, controlled by valve 33 into the pump l hereinbefore referred to.

Oil is continuously supplied by pump 38 to pipe 39 and, preferably passing through coil 22 in indirect heat exchange to the vapors in the upper part of column I1, is then carried through pipe 40 and discharged into pipe 8'. As illustrated, the pipe 8' is provided with a portion which projects into soaking drum 1 and upwardly therein while the pipe 40 projects into drum 1 and downwardly therein in such relationship as to discharge directly into the open end of pipe 8'. The amount of oil introduced through the pipe 40 should be sufficient to absorb the superheat of the cracked material withdrawn from the drum and by partial or complete vaporization of itself to provide sufficient cooling to partially condense the said cracked material. The extent of partial condensation should be sufficient to maintain the tar separating in II of sufficient fluidity for convenient handling.

An additional test of the quantity of oil to be introduced is that the vapors passing off in separator ll through the pipe l2 should be cooled to a temperature ranging between 500 and 700 F. The amount of oil to be introduced for this purpose will vary over wide limits depending upon the temperature of operation obtaining in the drum 1 and may range from a few percent up to substantially equal volumes in proportion to the cracked material withdrawn through the pipe 8.

The column ll operating to rectify the vapors after separation of tar, may yield a vapor passing overhead through pipe 23 consisting substantially of gasoline or may be only one of a series of rectifying towers making a preliminary separation.

I have found it particularly advantageous to supply through pipe 40 an oil containing a more volatile part suitable for cracking and a less volatile part which is unsuited for cracking. Such a stock is a treated pressure distillate bottoms.

It will be understood that the foregoing description is for purposes of illustration and that the invention is to be limited only by the appended claims or their equivalents in which it is my intention to claim broadly all novelty inherent in the invention.

I claim:

1. The method of cracking petroleum oil, which comprises heating the oil to a cracking temperature in an elongated narrow heating zone, introducing the heated oil into one end of an enlarged digesting zone wherein the oil is maintained for a substantial period of time without substantial loss of heat to effect the desired degree of cracking, continuously withdrawing the oil from a point within the digestion zone and near the opposite end thereof in a narrow confined stream initially directed downwardly, irijecting a relatively cold petroleum oil into said downwardly directed portion of the confined stream within the digesting zone in the direction of the stream and out of direct contact with the rest of the oil in the enlarged digesting zone, reducing the pressure on the oil during its passage through the narrow continuous stream outside the digesting zone and separating valuable products from the oil after the reduction of pressure.

2. Apparatus for cracking petroleum oils and obtaining gasoline therefrom comprising in combination a cracking coil, a soaking drum one end of which is connected thereto and which is adapt ed to receive cracked hydrocarbon material therefrom, a pipe for the withdrawal of cracked hydrocarbon material at the opposite end of said soaking drum having a portion projecting inwardly and upwardly in said soaking drum, a pressure reducing valve in said pipe, an oil supply pipe extending into and downwardly in said soaking drum and adapted to discharge into the said withdrawal pipe.

NATHANIEL E. LOOMIS. 

